Salts of bile acids act as detergents to solubilize and, consequently, aid in the digestion of dietary fats. Bile acids are derived from cholesterol. Following digestion, bile acids can be passively absorbed or reabsorbed by active transport.
Since bile acids are synthesized from cholesterol, reabsorption of bile acids from the intestine conserves lipoprotein cholesterol. Conversely, cholesterol levels can be reduced by hindering reabsorption of bile acids.
One method of reducing the amount of bile acids that are reabsorbed is oral administration of compounds that sequester the bile acids and cannot themselves be absorbed. The sequestered bile acids consequently are excreted. Cholesterol is then employed to produce more bile acids, thereby lowering the serum cholesterol level of the patient.
Polymers having cationic groups are particularly effective at sequestering bile acids. The efficacy of such polymers can be further improved by the incorporation of hydrophobic groups. However, the simultaneous incorporation of hydrophobic and cationic groups into a single polymer can be a synthetic challenge. Therefore, there is a need for novel bile acid sequestrants which provide an intimate association of cationic and hydrophobic groups in a readily prepared form.